A skateboard is basically constituted by a platform also called a board, having a given flexibility and two shafts provided at their ends with wheels mounted freely in rotation, said wheels carrying solid tires generally of elastomer, of a quality suitable for the desired maneuvers.
The shafts are each secured to a support carried by a block of elastomer material. This block has the ability to deform particularly proportional to the stiffness of the elastomer and this capacity of deformation permits orientations of the shaft relative to the longitudinal axis of the board.
The user, by his position on the board, can throw his weight to the side, to one side or the other, so as to obtain the desired deformation of the block and the desired orientation of the axles of the wheels. The skateboard can thus be piloted by the position of the user. Nevertheless, the angle of orientation remains small and the turning radius is large.
Such a vehicle remains difficultly controllable particularly when the board is of a great length called a “long board”, however it would be useful to be able to make sharper curves.
In the particular case of a device with pneumatic tires and if desired driven, French patent application No. 2 784 302 discloses an arrangement with a deformable parallelogram which accentuates the turning effect and above all permits inclination of the wheels. Such an arrangement, in addition to being mechanically complicated, is incompatible with a skateboard having low clearance as is necessary to facilitate climbing and to ensure perfect balance by keeping the center of gravity as low as possible. Moreover, the control of the deformation of the parallelogram remains a problem not solved by this patent application.
This deformable parallelogram mounting must be reserved for large sized devices, with a high clearance and pneumatic tires.
U.S. Pat. No. 5,540,455 provides an improvement to greatly increase the steering capability. Thus, this patent proposes a platform with two platforms articulated to each other. The user then places one foot on each platform and can orient each as desired. A spring is interposed to constitute this articulation.
This permits increasing the number of combinations of orientations of the shafts, but it will also be seen that steering such a structure is sensitive because the orientations of the two shafts can be opposed, which gives rise to extreme or even dangerous movements. Moreover, the two portions can be inclined in the longitudinal direction also forming a V with the axis of movement, which is not satisfactory.
European patent application No. 0 933 103 discloses an arrangement with oscillating arms mounted on a pivotal platform. If such an arrangement can give rise to certain comfort relative to the surface on which the skateboard moves, it does not solve the problem of turning whilst having perfect control of this turning. Moreover, the complexity of such an arrangement makes it incompatible with market conditions or limits it to the elite.